Tube reducing machine



1961 D. v. sTRocK TUBE REDUCING MACHINE l6 Sheets-Sheet 1 Filed March 3, 1954 STROCK Hand/p IVJCIW ATTYS.

21, 1961 D. v. STROCK TUBE REDUCING MACHINE 16 Sheets-Sheet 2 Filed March 3, 1954 INVENTOR. DONALD V.

STROCK fimw WJ/M ATTYS Feb. 21, 1961 D. v. STROCK 2,972,267

TUBE REDUCING MACHINE Filed March 3, 1954 16 Sheets-Sheet 3 L 4 INVENTOR. FIG, 3 DONALD v. STROCK BY ATTYS Feb. 21, 1961 D. v. STROCK TUBE REDUCING MACHINE 16 Sheets-Sheet 4 Filed March 3, 1954 V STROCK ATTYS Feb. 21, 1961 0. v. STROCK TUBE REDUCING MACHINE 16 Sheets-Sheet 5 Filed March 5, 1954 INVENTOR.

DONALD v 7 STROCK I ATTYS Feb. 21, 1961 v, s oc 2,972,267

TUBE REDUCING MACHINE Filed March 3, 1954 16 Sheets-Sheet 6 I27 I30 7 I29 54 INVENTOR. DONALD V. STROCK ATTYS.

Feb. 21, 1961 D. v. sTRocK TUBE REDUCING MACHINE- 16 Sheets-Sheet 7 Filed March 5, 1954 IN VEN TOR.

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DONALD V. STROCK uLH ATTYS Feb. 21, 1961 D. v. STROCK TUBE REDUCING MACHINE Filed March :5, 1954 16 Sheets-Sheet 8 INVENTOR. DONALD V. STROCK ATTYS Feb. 21, 1961 D. v. STROCK 2,972,267

TUBE REDUCING MACHINE I Filed March 5, 1954 16 Sheets-Sheet 9 FIG. l2

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INVENTOR. 25 DONALD V. STROCK 26 M flan,

ATTYs.

Feb. 21, 1961 v, STROCK 2,972,267

TUBE REDUCING MACHINE l6 Sheets-Sheet 10 Filed March 3, 1954 34 FIG. I6 A" FIG. l4

Q l7l Q Q i I i C 276 :1: 275- C275 280 Z-2eo 21a 1 FIG l5 J I 279 k J K 25 INVENTOR. DONALD v. STROCK Q A k A ATTYS.

Feb. 21, 1961 D. V. STROCK TUBE REDUCING MACHINE Filed March 3, 1954 ISO l6 Sheets-Sheet 11 ZIG FIG. I7 20 INVENTOR.

DQNALD V. STROCK ATTYS Feb. 21, 1961 p. v. STROCK TUBE REDUCING MACHINE l6 Sheets-Sheet 12 Filed March 3, 1954 2 s c mm .TY. r T W n NS m mv D l- MM M m Y B ONOE won mmm 3 mo 5N mo non an 22.2.... .1 3 Q No Feb. 21, 1961 D. v. STROCK TUBE REDUCING MACHINE l6 Sheets-Sheet 13 Filed March 3, 1954 INVENTOR. DONALD V. STROCK BY M,

ATTYS Feb. 21, 1961 D. v. sTRocK 2,972,267

TUBE REDUCING MACHINE Filed March a. 1954 16 Sheets-Sheet 14 FIG. 24

INVENTOR. DONALD V. STROCK BY M,

ATTYS Feb. 21, 1961 D. v. STROCK TUBE REDUCING MACHINE l6 Sheets-Sheet 15 Filed March 3, 1954 E f x. M m l: V 5 QU J a X 2 U m H m Feb. 21, 1961 Filed March 3, 1954 D. V. STROCK TUBE REDUCING MACHINE 16 Sheets-Sheet 16 FIG. 26

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1 1" 314 39: 386 i I) P366 /INVENTOR.

DONALD V. STROCK TUBE REDUCE? G MACHINE Donald V. Strock, Poland, Ohio, assignor to The Aetna- Standard Engineering Company, Pittsburgh, Pa., a corporation of Ohio Filed Mar. 3, 1954, Ser. No. 413,742

1 Claim. (Cl. 80-14) This invention relates to tube reducing machines in which tubing is rolled on a mandrel by grooved die rollers in order to elongate the tubing and to reduce its wall thickness and diameter.

Machines of this general type are well known and comprise a drive mechanism by means of which a roll supporting saddle is reciprocated on a horizontal frame. The saddle carries a pair of die rolls having opposed grooves adapted to do work on a tube interposed between the rolls. As the saddle reciprocates the rolls are rotated by engagement between gears or the like mounted on the rolls and racks or the like mounted on the frame on which the saddle reciprocates. A mandrel is provided which extends into the space within the grooves of the rolls and which functions to support the tube during the rolling operation. Means are provided to advance and retract the mandrel so that tubes can be placed on the mandrel. In operation, the tube being operated upon by the rolls is intermittently advanced through the rolls by means of acarriage which pushes the tube through the rolls and the tube is grasped by chucks, clamps or the like to rotate it intermittently. The dies are arranged so that they are disengaged from the tube at each end of the stroke of the saddle. During 2,972,267 Patented Feb. 21, 19 61 7 V v 2 l ports to prevent the mandrel from buckling under the forces exerted upon it by the rolling operation and the provision of a simple yet rigid and accurate frame structure whereby the proper positioning of the mandrel is assured.

- Other objects include the provision of improved carriage means for advancing the tube into the dies, the provision of improved means for holding and rotating the tube as it is being worked on by the dies; the provision of improved hydraulic mechanisms for driving the tube advancing carriage and for clamping and rotating the tubes.

Additional objects include the provision of improved means for rapidly loading a tube to be fed to themachine onto the mandrel; the provision of a loading rack for the storage of tubes disposed above the saddle and die mechanism of the machine so that it requires no additional floor space; the provision of a loading rack that can be moved out of the way rapidly and easily to give access to the saddle; the provision of means for rapidly and easily transferring a tube from the loading rack and pushing it onto the mandrel, and the provision of means the time of disengagement of the dies when the saddle is near the inlet end of the machine, the tube being worked upon is advanced a slight distance and during the time that the tube is disengaged by the dies when the saddle is toward the discharge end of the machine, the tube is rotated through a fraction of a turn, for example, sixty degrees.

The general objects of the present invention are to provide an improved tube reducing machine, to provide a more reliable and more accurate tube reducing machine, to provide a tube reducing machine which will 'have increased production as compared to existing machines and to provide a tube reducing machine which will occupy a substantially smaller amount of floor space than existing machines having the capacity to handle tubing of the same size.

More specific objects include the provision of an improved saddle construction in which the die supporting rolls are readily removable; the provision of a saddle that is accurately and smoothly guided-in its reciprocating movement; the provision of a saddle embodying a hydraulic pressure relief mechanism to prevent damage to the dies and the mechanism in the event of overloads;

' 5-5 of Figure 1a.

the provision of a simple and eificient drive mechanism for reciprocating'the saddle in which the saddle is reciprocated by connecting rods that are maintained in tension during the working stroke of the saddle, and in which the angularity of the rods is kept at a minimum; the provision of an improved mandrel advancing and retracting mechanism whereby the mandrel may be rapidly retracted from working position to loading position and rapidly advanced to working position and in which the mandrel is accurately located with respect to the dies in the working position; the provision of improved sup dicated by the line 12-12 of Figure" 11.

whereby the mandrel in. position to be loaded is disposed substantially in alignment with the pusher employed to push the tubes onto the mandrel.

Further objects and advantages of the invention will become apparent from the following description of a preferred form thereof, reference being made to the accompanying drawings. The essential characteristics of the invention are summarized in the claim.

Referring now to the drawings,

Figuresl and 1a together constitute a side elevation of the complete machine.

Figure 2 is a side elevation of the saddle mechanism on an enlarged scale as compared to Figure 1.

Figure 3 is a vertical section on an enlarged scale through the saddle and its support taken as indicated on the line 33 of Figure 2.

- Figure 4 is a central, longitudinal vertical section through approximately the same portion of the apparatus as shown in Figure 2 and on the same scale as Figure 2 and illustrating the arrangement of the die rolls, mandrel and chucks with respect to the work, the section being taken as indicated by line 4-4 of Figure 3.

Figure 5 is a plan view on an enlarged scale of the drive mechanism with the upper half of the housing removed, the view being taken as indicated by the line Figure 6 is a longitudinal sectional view on an enlarged scale of one of the tube grasping and rotating chucks, the section being taken as indicated on the line 6--6 of Figure 4.

Figure 7 is a transverse section as indicated by line '7-7 of Figure 6.

tion of the entry end of the apparatus remote from the working rolls, the view' being taken as indicated by line 88 of Figure 1.

Figure 9 is a plan view on the same scale as Figure 8 of an intermediate portion of the entry end of the apparatus, the view being takenes indicated by the line 99 of Figures '1 and 1a.

Figure 10 is a horizontal section view showing the drive mechanism for the tube advancing carriage, the support for the mandrel, and the carriage, the figure being taken as indicatedby the line 1010 of Figure 1 but on an enlarged scale.

the line 11-11 of Figure 10.

Figure 12 is a transverse vertical section taken as in- Figure 8 is a plan View on an enlarged scale of a por- Figure 13 is a transverse vertical section taken as indicated by the line 13-13 of Figure 11.

Figure 14 is a horizontal sectional detail showing the supports for the carriage advancing screws adjacent the saddle mechanism, thesection being taken along the line 14-14 of Figure 2. V i

Figure 15 is an enlarged vertical transverse sectional view taken on the line l-15 of: Figure 2. v

Figure 16 is a vertical longitudinal section taken as indicated by the lineld16 of Figure 15.

Figure 17 is a diagrammatic illustration of the screw and mandrel support blocks showing the sequence of movements of the carriage nad the mechanism by which it spaces the support blocks.

Figure 18 is a side elevation of the mandrel loading mechanism.

Figure 19 is an end view of the mechanism of Figure 18, on an enlarged scale, the view being taken as indicated on line 19-19 of Figure 18.

Figure 20 is a transverse section through the loading rack showing the hydraulic and chain mechanism for raising and lowering parts of the rack, the section being taken on line 2ii-2 of Figure 18.

Figure 21 is a plan view of the loading rack taken as indicated by line 212l of Figure 18.

Figure 22 is a transverse section taken as indicated by line 22-22 of Figure 21.

Figure 23 is a section through the main gear taken as indicated by line 323 of Figure lav Figure 24 is a fragmentary section through one of the carriage supporting slides, taken as indicated by line 24-24 of Figure 2.

Figure 25 is a diagram of the hydraulic system for advancing the carriage and the tube; and

Figure 26 is a diagram of the hydraulic system for rotating the tube.

General arrangemenL-The general arrangement of the entire apparatus is illustrated in Figures 1 and 1a and in the enlarged views constituting Figures 2, 3 and 4. As there shown, the rolls 1% and lit which are provided with die recesses for working on a tube T are supported in or by a saddle 12 which reciprocates on tracks 14 carried by the supporting frame structure 15. The frame structure 15 is provided with fixed racks 16. Roll 11 has gears 17 that engage the racks and thetwo rolls are geared together as described below so that when the saddle is reciprocated the rolls are rotated first in one direction and then in the'other. The saddle is reciprocated on its tracks by means of the main drive mechanism indicated in general at 2% and disposed at the exit or discharge end of the apparatus. The main drive mechanism includes cranks 21. (see Figure 5); connecting rods 22 connect the cranks to the saddle 12. The crank shaft is rotated in the direction of the arrow in Figure la ordinarily at a speed of about 60 revolutions per minute, although this may be varied throughout a considerable range. The tube T is fed in from the left in the arrangement shown in the drawings and is discharged to the right so that the working stroke of the dies contained in rolls it and 11 takes place as the saddle moves from left to right, hence the connecting rods are in tension during each working stroke.

The tube T is supported in proper position with respect to the die rolls by a mandrel M, the tapered point P of which (see Figure 4) is disposed between the rolls when the machine is operating. The mandrel can be withdrawn so that another tube can be loaded thereon; the subframe member 25 supports the mandrel and its advancing and retracting mechanism and also supports the tube advancing means. Member 25 preferably comprises an H-beam and is securedat one end to-the main frame 15 whileits other end is supported on a foundation plate 26. The actual support for the mandrel and tube advancing mechanisms is provided by the tiltable frame member 2'7 which is also an Hbeam and which is pivotally confit nected to the subframe 25 as at 28. The tiltable frame member 27 carries the rear support 30 for the mandrel, the cylinder 31 which advances and retracts the mandrel, the mandrel locking mechanism 32 which accurately locks and retains the mandrel in its advanced positions, the tube advancing carriage 33, the tube advancing screws 34 and associated mechanisms, all of which are described in detail below.

In order to provide for convenient loading of tubes on the mandrel when it is in retracted position, a hydraulic cylinder and piston mechanism 37 is mounted on trunnions 33 carried by the subframe member 25; the mechanism embodies a piston rod which is pivotally connected as at 39 to the tiltable frame 27. Operation of the cylinder functions to raise the tiltable frame to the position shown in broken lines in Figure 1 wherein it is in alignment with a pusher mechanism indicated in general at 40 in Figure 18; the pusher is associated with a load.- ing rack indicated in general at 41 in Figures 1a and 18. The loading rack is disposed above the saddle and main drive mechanism and is adapted to carry a supply of tubes to be operated upon by the machine. The pusher mechanism 40 is tiltable from a horizontal position to a posi tion in alignment with the raised position of the tiltable frame 27.

The tubes are intermittently advanced through the machine by the carriage 33 and are guided and held in proper position with respect to the dies by a chuck 45 disposed adjacent to entry end of the rolls 10 and 11 and a substantially identical chuck 46 disposed beyond the delivery or exit end of the rolls 10 and 11. These chucks grip the tube and also function to rotate the tube through about 60 when the dies have completed their working stroke and are disengaged from the tube preparatory to beginning the return stroke of the saddle. Carriage 33 is operated to advance the tube step by step at the time that the saddle has completed its return stroke and is dis posed at its extreme position near the the entry end of the apparatus. The step-by-step operation of the carriage and the step-by-step rotation of the chucks 45 and 46 are preferably obtained by hydraulic mechanisms, the hydraulic pressure being supplied by a hydraulic system controlled in synchronism with the movement of the saddle, the parts being driven by appropriate hydraulic motors. The hydraulic circuits are described in detail below and are illustrated in Figures 25 and 26 of the drawings.

Saddle and associated mechanisms-The actual work of reducing tubes fed into the machine is done by the die rolls 10 and 11 carried by the saddle 12. These parts and their associated mechanism are shown particularly in Figures 2, 3 and 4. As indicated in Figures 2 and 3,

the saddle 12 consists of two heavy U-shaped side members 5t) and 51 connected at the bottom by a connecting bar 52, the recesses in the U-shaped side members providing supports for the bearings for the necks of rolls 10 and 11 and the rolls themselves being disposed between the two side members as shown particularly in Figure 3. The bearing blocks 53 and 54 for the lower roll It simply rest on the bottoms of the inner surfaces of the Us and are guided by the inner vertical surfaces of the legs of the Us while the bearing blocks 55 and 56 for the upper roll 19 are guided by the inner'surfaces of the vertical legs of the Us and rest on the uppersurfaces of the bearing blocks 53 and 54. When the bearing blocks are so positioned, the rolls 10 and 11 are directly in engagement with each other as illustrated. The bear ing blocks carry appropriate anti-friction bearings, as shown.

In order to hold the bearing blocks 55 and 56 and the roll ill down against the forces exerted in the operation of the machine, the open ends of the Us are closed by caps 57 and 58 which are secured .to the U-shaped portions 50 and 51 by pins 59 as shown. In order to retain the rolls in proper position under the large forces that are developed in operation, and at the same time to permit the rolls' to separate if the forces become excessive and thereby to prevent breakage of the machine, hydraulic cylinders 60 and 61 are formed in the caps 57 and 58 respectively. Pistons 62 and 63 are disposed within these cylinders and integrally formed ,piston rods 64 and 65 bear downwardly upon the bearing blocks 55 and 56 to maintain the desired pressure on the rolls. The pressure is maintained by check valves 66 and relief valves 67 shown diagrammatically in Figure 3 which are arranged to maintain a suitable pressure in the cylinders 60 and 61, for example, pressures of the order of 5,000 pounds per square inch are contemplated and pressure relief valves 67 are arranged to open when the pressure substantially exceeds the desired pressure. Thus, for example, if the pressure should reach 5,500 pounds per square inch, upon opening of the pressure relief valves, the pistons 62 and 63 can move upwardly within the cylinders 60 and 61, the roll can lift away from the roll 11 and the possibility of developing destructive forces in the apparatus due to improper functioning of the rolling mechanism or the improper design of dies or the like is eliminated.

The saddle is supported for reciprocating movement by cross-bars 70 and 71 at the entry and exit ends, respectively, of the saddle, see Figures 2, 3, 4 and 24; these bars rest on pads or bearing surfaces 72 and 73 which, in turn, are carried by tracks 14. Sideways movement of the saddle is prevented by downwardly extending flanges 74 and 75 on the pads 72 and 73. The tracks 14 are supported by the top edges of the vertical side panels 81 of the frame these panels being cut out as shown at 82 in Figures la and 2 to accommodate the movement of the saddle and to permit removal of the rolls.

The cross-bars are welded to wings 91 and 92 extending longitudinally from the saddle members 50 and 51, the positioning of the cross-bars at the extreme ends of the saddle giving a long base for support of the saddle and thus assuring smooth motion and accurate guiding of the saddle. I

In order to rotate the rolls as the saddle reciprocates, racks 16 are mounted in the side pieces 81 at a level beneath the tracks 76 and 77, the shaft of roll 11 is extended from both sides of the machine as shown and gears 17 are keyed to the roll shaft and engage the racks; thus, as the saddle reciprocates the roll 11 is constrained to rotate and the rotation of roll 11 is transmitted to roll 10 through gears 94 on the shaft of roll 11 which engages gears 95 on the shaft of roll 10. See Figures 1a, 2 and 3.

The racks 16 are secured and vertically positioned in the frame in engagement with gears 17 by means of wedges 96 clamped between the slanting ends 97 of the racks and adjacent shoulders 98 formed by the opposed projections 99 of theside pieces 81 by means of bolts 100 which extend through the wedges into each projection. As shown in Figure 2, slanting surfaces on the wedges engage the complementary slanting surfaces 97 on the racks 16 and securely position the racks when the bolts 100 are drawn up.

By this construction, rolls 10 and 11 readily can be removed from the saddle for replacement. This is accomplished by loosening the bolts and wedges 96.

and removing the racks transversely from the fr'ame. Then, with the saddle 12 positioned so that. the axesof the rolls are approximately at the center of the opening 82 in the side panels 81, the caps 57 and 58 are removed and the rolls 10 and 11 lifted vertically out of the saddle.

The construction of the rolls themselves and the manner in which they operate on tubing is illustrated in Fig ure 4. In this figure the full line position of the saddle and rolls shows them approximately at their. extreme position adjacent the entry end of the apparatus,: while the broken 'line' indicates the position the saddle takes adjacent the exit end of the apparatus; The tube T ex tends within the, die groove of the rolls and the tapered .point P of themandrel M supports the tube against the action of the rolls. In the extreme position shown the grooves of the rolls are sufliciently large so that the rolls do not engage the tubing with any substantial pressure. When the saddle and rolls are adjacent the entry end of the apparatus, the tubing is advanced a fraction of an inch. Then as the rolls roll on the tubing toward the exit end of the machine, the grooves 101 and 102, which are progressively reduced in cross-sectional area, act on the tube to elongate it and reduce its diameter and wall thickness. When the saddle reaches the broken line position the relieved portions 103 and 104 of the grooves are adjacent the tube, and the rolls are substantially disengaged from the tube. The tube is then rotated approximately 60 so that as the rolls roll back on the previously reduced section of the tube, they round it more accurately and eliminate the formation of any fins between the dies. As the rolls approach the extreme position at the entry end of the apparatus, the rolls disengage the tube, the tube is again advanced and the operation repeated. This is carried on at a relatively high rate of speed, depending on the size of the tube, about 60 complete reciprocations per minute being customary and as much as 120 strokes being possible on small tubes. It will be noted that the actual working portions 105 and 106 of the rolls are formed separately, these portions being held in place by studs 107 and 108 and accurately located by interfittin-g tongues and grooves 109, 110, 111 and 112, as shown in Figure 3. The separate formation of the die portions of the rolls provides for economy in the manufacture of dies to produce tubing of various sizes and in the replacement of worn dies. Main drive-The main drive for the saddle is illustrated in Figures 1a, 5 and 23. As noted above, the saddle 12 is reciprocated by connecting rods 22 which are pivotally connected to the saddle as at 113. It will be noted that the pivots 113 are disposed substantially in the plane of the center line or pass line of the rolls 10 and 11. This alignment of the pivots and the pass line minimizes the vertical components of the forces applied to the saddle. r

The cranks 21 to which the connecting rods 22 are secured are driven by the main drive motor (not shown) through the reduction gearing constituting the main drive mechanism 20, which is illustrated with the top half of the housing removed in Figure 5. The drive preferably is through a flexible coupling or clutch 114, one element of which is connected to the main drive motor and the other element of which is connected to the input shaft 115. Clutch 114 preferably is a coupling of the Airflex type in which the friction elements are held together by pneumatic pressure and which is arranged -to slip under predetermined over loads such as, for example, fifty percent (50%), thus protecting the motor and the equipment in case of jamming of the apparatus.

From shaft 115, the drive isthrough pinion 116, gear 117, countershaft 118, pinion 119 and gear 120 to crankshaft 121. Cranks 21 are mounted on the ends of shaft 121 and the rotation is preferably in the direction shown by the arrow in Figure la so that the angularity of the connecting rod with respect to the path of movement of the saddle is kept at a minimum during the working stroke of the saddle.

It will be noted that the center lines of the shafts 115, 118 and 121 are disposed slightly below the pass line of the rolls 10 and 11 and that the gears and pinions 116,

117, 119 and 120 are disposed on either side of the pass line of the roll as shown particularly in Figure 19. This arrangement makes it possible to provide the upper half 122 of the housing 20 with a guide tube 123 through which the completed tubes can pass as they leave the machine.

Tube holding and rotating chucks.--The chucks and 46 disposed at the entry and delivery ends of the apparatus, respectively, see Figures 1a and 2, function to hold the tubes as they are being operated on by the die rolls 1% and 11 and to rotate the tubes at the end of the working stroke of the dies. The chucks are arranged to assist in holding the tubes against the thrust exerted upon them during the working and return strokes of the dies, yet to permit the tubes to be advanced through the chucks. The chucks also grip the tube with sufficient firmness so that when the chucks are rotated the tubes are also rotated. Preferably the chucks are disposed close to the die rolls, chuck 45 being supported by the transverse vertical member 125 of the main supporting frame 15 while the chuck 46 is supported by the transverse vertical member 126 of the frame 15. The chucks are preferably of identical construction and accordingly only chuck 45 will be described in detail herein.

As shown particularly in Figures 6 and 7, chuck 45 comprises a housing or body 127 having a radially extending flange that is bolted to the transverse frame member 125. A cylindrical portion 129 of the housing projects through the cross-member, the cross-member being recessed to receive the cylindrical portion so that the chuck can be removed and replaced simply by sliding it longitudinally out of the hole in member 125.

Cylindrical portion 129 has an internal cylindrical surface within which is disposed a hollow tubular clamping piston 130, piston 13% being provided with piston rings 131 and having sleeve portions 132 and 133 that extend through packing members 134 and 135. Ports 136 and 137 are provided in the wall of cylindrical portion 129, the arrangement being such that when fluid under pressure is admitted through appropriate fluid connections to port 136, piston 132 is moved to the right in the embodiment shown in the drawing and when fluid under pressure is admitted through port 137, piston 132 is moved to the left.

In order to provide means for clamping a tube within the chuck, a camming sleeve 133 is supported within piston 132 by means of roller thrust bearings 139. The sleeve is thus mounted for rotation with respect to the piston but is constrained by the bearing to move longitudinally with the piston. The forward, or right, end of the sleeve is enlarged as at 14th and carries a camming ringldil. Ring 1.41 is adapted to engage the outer camming surfaces 142 of the resilient gripping fingers 143 of the collet or gripping member 144'. The fingers are provided with separately formed gripping pads 145 which engage the exterior of the tube T. Collet 144 is mounted on the end of a rotatable collet-supporting sleeve 146 which is supported for' rotation within the chuck body and held against longitudinal movement by roller thrust bearings 1 57.

It will be seen that with this arrangement, whenfluid under pressure is admitted through port 136 and clamping piston 130 urged toward the exit end of the apparatus or to the right as shown in the drawing, then the camming sleeve 13% is likewise carried to the right. Collet 144, however, is held against longitudinal movement by sleeve 146 and thrust bearings 1 3-37. The resultant relative longitudinal movement between the collet and the camming ring 141 causes the ring to urge the resiient gripping fingers 143 inwardly causing the pads 145 to grip the tube. The gripping pressure can be controlled by varying the fluid pressure admitted through the port 136, and the collet can be released by releasing fluid through port 136 and supplying fluid under pressure through port 137. it will be noted that forces exerted by frictional engagement of the tube with the collet tend to reduce the clamping forces exerted on the tube as it moves in the advancing direction (to the right in the drawing) while forces exerted by the tube in the opposite direction tend to increase the clamping pressure.

In order to rotate a tube gripped by the collet 144, the cumming sleeve 13%, collet 1 44 and supporting sleeve 146 are arranged to be rotated as a unit with respect to the body 127. Rotation is accomplished by a worm wheel 14% which is keyed to sleeve 146; the worm Wheel is rotated by worm 14% which is supported by appropriate bearings 151 and 152 in an enlarged portion 153 of the housing 127. T he worm in turn is driven through a suitable coupling 154 by a hydraulic motor 155 (see Figure 2). Motor 155 is of the positive displacement type, suitable hydraulic motors being manufactured by the Vickers Manufacturing Company of Detroit, Michigan, so that for a given volume of fluid passing through the motor, the motor makes a given number of revolutions. Thus by supplying the same quantities of liquid to the motor 155 of chuck 4-5 and the motor 156 of chuck 46, they can be caused to rotate each of the chucks or gripping jaws through the same number of degrees. The hydraulic circuits whereby the motors for the chucks 45 and 46 are rotated through the desired number of revolutions in proper time relationship with the movements of the saddle are described below. When the sleeve 146 and collet 144 are rotated, the sleeve 138 also rotates because of the frictional engagement between the clamping ring 141 and the outer camming surfaces 142 of the fingers 143 of the collet.-

Tube feeding carriage and associated mechanisirz. Tubes mounted on the mandrel M are pushed forward in a step-by-step motion through the die rolls and chucks by the tube feeding carriage 33 which travels along the tiltable frame member 27 from its rearrnost position shown in Figure 1 to a position adjacent the saddle mechanism and main frame 15. As shown in Figures 8, 10, 11 and 13, the carriage 33 comprises a block 160 extending transversely of the frame member 27 and having a central recess 161 provided with a shoulder 162 acting as a stop abutting the rear end of the tube T, the recess 161 continuing in reduced diameter toward the rear of the machine from shoulder 162 to provide a passageway for the mandrel M. During normal operation, the tube T is held within opening 161 of the carriage and against shoulder 162 by the compressive forces resulting from the forming rolls acting on the tube and hence no other locking means is necessary to secure the tube to the carriage. However, in the event it should become necessary to withdraw a partially reduced tube from the machine as, for example, when the tube is faulty, the tube must be clamped to the carriage as the latter is withdrawn. For this purpose, a set screw 163 is threaded into the block 16% and is adapted to clamp the end of the tube T to hold it in the recess 161 when the carriage 33 is moved away from the rolls.

On either side of the recess 161, the block 16% is provided with generally rectangular recesses which receive nuts 164 (see Figure 10) that are threaded on the longitudinally extending carriage drive screws 34. Nuts 164 are retained in position within the block by flanges 165 and 166 on the front and rear sides of the carriage, respectively.

In order to support the carriage in its travel along the frame member 27, a plate 167, see Figure 13, is welded to the horizontal web 168 of the frame member 27, the plate 167 extending substantially throughout the length of travel of the carriage. Slides 169 preferably composed of brass or a similar metal are suitably secured to the upper surface of the plate 167; the'lower surfaces of the nuts 164 slide along and are supported by the upper surfaces of the slides.

With this arrangement, rotation of the screws 34 in one direction causes the carriage to advance toward the saddle mechanism 12 while rotation of the screws in the opposite direction causes the carriage to retract. In order to support the screws 34 for rotation, the forward ends of the screws adjacent the saddle 12 are mounted in thrust bearings 171, see Figure 14, which are mounted in blocks 172 secured tothe end plate 173 of the tiltable 

